Selector device for automatic typewriters



Sept. 18, 1951 e. F. CARLSON 2,568,113

SELECTOR DEVICE FOR AUTOMATIC TYPEWRITERS Filed March 12, 1949 I 4 Sheets-Sheet 1 INVENTOR. V Gustav E Carlson f z' w/ zzzm @s.

Sept. 18, 1951 c so 2,568,113

SELECTOR DEVICE FQR AUTOMATIC TYPEWRITERS Fi led March 12, 1949 4 Sheets-Sheet 2 INVENTOR. Gustav F. Carlson Sept. 18, 1951 G. F. CARLSON SELECTOR DEVICE FOR AUTOMATIC TYPEWRITERS 4 Sheets-Sheet 5 INVENTOR. Gustav F1 Carlson BY m9? Filed March 12, 1949 Sept. 18, 1951 e. F. CARLSON 2,568,113

SELECTOR DEVICE FOR AUTOMATIC TYPEWRITERS Filed March 12, 1949 4 Sheets-Sheet 4 92 46 Q ZZMM Patented Sept. 18, 1951 OFFICE SELECTOR DEVICE FOR AUTOMATIC 'TYPEWRITERS Gustav F. Carlson, Chicago, Ill.

Application March 12, 1949, Serial No. 81,049

12 Claims.

This invention relates to a pneumatic key operating action for use in selectively operating the keys of typewriters or other devices having a plurality of elements adapted to be selectively moved through the control of a record sheet. While the present invention will be described herein as a pneumatic action for typewriters, in particular, electrically driven typewriters, it will be understood that, instead of using the device for operating a typewriter, other devices having a plurality of keys or levers may be operated, for instance, a punching device for perforating a record sheet.

The prior art shows instances of pneumatic key operating actions for use in selectively operating keys of a typewriter, but these prior art pneumatic actions are complicated, occupy a large space and are not easily attached to or detached from a typewriter. A particular defect in prior art pneumatic actions is the fact that these prior art actions include a number of sealing diaphragms within a closed box or chest that can be replaced only by taking the box or chest apart. This is a serious disadvantage because these diaphragms are ordinarily the first part of the action to require replacement or repairs. 7

'I have now provided a novel pneumatic action comprising a selector devic or pouch box defining an inner chamber adapted to be maintained under reduced pressure. A plurality of cells are defined on the inside of this chamber and sealed off from the chamber by a flexible diaphragm. Each cell communicates directly with a tracker bar aperture to which air is selectively admitted through record sheet perforations. Normally, each cell is kept under a pressure not much higher, if at all, than the pressure in said chamber, and admission of air into a cell will cause the corresponding diaphragm to move outwardly within the chamber. Such movement actuates one end of a lever fulcrumed in a slot extending through a selector or pouch box wall, the other end of the lever extending outside of the selector or pouch box. Each of these lever slots is closed off from the atmosphere by a, centrally perforated flexible diaphragm through which the lever extends. The inner margin of each diaphragm is sealingly attached to each lever at the fulcrum point of the lever, while the outer margin is sealingly attached to the outside of the" pouch box. These sealing diaphragms are the first members to require replacement or repairs and, being placed on the outside of the selector or pouch box, are easily accessible. Further, the levers actuated by the di-aphragms closing off the cells from the pouch box chamber can all be made of the same length and so disposed as to all project from one side of the selector or pouch box. Hence, for actuating the typewriter keys I can use a second set of levers of various lengths extending over and beyond the side of the selector or pouch box and each having one end readily attached to a typewriter key lever. Thus, the pneumatic action can easily be attached to a typewriter or the like.

It is, therefore, an important object of the present invention to provide a pneumatic action for selectively operating a typewriter or the like and characterized by extreme simplicity, ease of repair and ease of attachment to and detachment from the mechanism to be selectively operated.

Other and further objects and features of the present invention will become apparent from the following description and appended claims taken in conjunction with the accompanying drawings which show, by way of an illustrativ example, a pneumatic action according to the present invention as operatively connected to a typewriter. More particularly:

Figure 1 is a side elevational view, with parts shown in vertical section and other parts broken away, of a typewriter equipped with a pneumatic action according to this invention, the typewriter being mor or less schematically illustrated;

Figure 2 is a perspective view of a tracker bar forming part of the pneumatic action shown in Figure 1, a record sheet being shown in broken lines;

Figure 3 is a cross-sectional view taken along the line 33 of Figure 1, with parts broken away;

Figure 4 is a cross-sectional view taken along the line 44 of Figure 3, with parts broken away;

Figure 5 is a fragmentary cross-sectional view taken along the line 5-5 of Figure 4;

Figure 6 is a horizontal longitudinal crosssectional view through the tracker bar take along the line 6--6 of Figure 1;

Figure 7 is a cross-sectional View taken along the line 'l'! of Figure 6;

. Figure 8 is a cross-sectional view taken along the line 8-8 of Figure 6;

Figure 9 is a cross-sectional view taken along the line 99 of Figure 3 and showing the key parts of a typewriter in two operating positions:

Figure 10 is a cross-sectional View taken along the line l0l 0 of Figure 3; and

Figure 11 is a view taken along the line ll-I l of Figure 9 but showing a lever having fiat sides. Referring to the drawings, and more particularly to Figure 1, the reference numeral l0 designates a supporting frame and housing for a pneumatic actuating mechanism. This frame includes a portion l2 providing a support for a typewriter or such implement having a plurality of keys or levers to be actuated. In the drawings, particularly in Figure 1, the reference numeral 14 designates a standard typewriter having a plurality of keys l6 and key levers or key bars l8 extending horizontally from the'ke'yboard'un'der the forward part of the frame of the machine and operative to transmit motion to the type bars and other elements to beac'tuated. The construction of the typewriter per se forms no part of the present invention, and for this reason is not described in detail herein. I note, however, that the actuating mechanism of the present invention is particular "jly adapted for use in connection with an elec trically driven typewriter of standard construction.

As best shown in Figures 1, 3 and 9, the bars Hlv are directly actuated by connector strips equal: in number to the bars I8. Each strip-2D has its upper end bent, as indicated at 20a, and theseybent strip endsrest upon the upper surface of the bars l8'sothat the" strips 20 may be con-' sidered: as each depending from the bar 18'. As shown, the strips 20 are of approximately the same' length. For preventingall but longitudinal movement of the:strip 20-, I provide means including a plurality of spaced bolts" 22' extending upwardly from the: supporting member l2 bebind the strips 28; The back-bones of each of two pairs of. comb like members 24 are each clamped-at different elevations onto the bolts 22 by nuts 26; I heteethof the" combs 24- project forwardl-y between the stripsZG; Metal strips 28 are loopedza'roun'd the'teeth of each'pair of combs 24-in front of thestrips 20. Thus,. each strip 20 isguided' in its longitudinal movement by two aligned apertures: defined at two difierentlevels by adjacentteeth of'the combs 24; by the bottoms of the-slots between these teeth and by the strips 28; The lower ends of each of the connectorstrips 20 are perforated, and thehooked ends30'a of connector wiresSEl a're threaded through these apertures; Asbestshown in Figure3, the connector-wires 30 arethus suspended from the connector: strips 20; The-lower endstflbof theconhector wires are also booked andthreaded through the flattened perforated ends 32a ofoperating levers 3-2: projecting from a selector-mechanism or pouch box'34'; The wires 30 are of different lengths, for operative connection to -the levers 32- projectingafrom the pouch box 34- at differentlevels, as will be explained hereinbelow; As shown in Figures 1, 3 and 9, the pouch box 34; is suspended from the supportinglmember l2 by zthre'e U-r'shaped wires 36 encompassing the pouch box and having their ends, projecting up through apertures inthe supporting member l2. Nuts 38-. are threaded on the free ends of the wires 36 and are tightened so that" the" pouch box" 34 will be: securely clamped to the underside of the supporting member I 2.

As -best show'n imFigures9 and 10, the pouch box 34 is made up of a pluralityof rectangular frames 40;"a plurality of boards 42'equal in numher to the'frames 40 and alternating therewithso that-a board'42' extends below each frame; and an uppermost-cover 44 immediately below the supporting member [2. A thin flexible leather diaphragm lfi is'super'impo'sed on each b'oard'42, The assembled parts formingthe pouch box- 34 maybe'held'together bythe wires 36 as anchored bythe nuts38* on the 'supportingmember [2. To-

4 r seal the pouch box 34, the leather may be clipped in rubber latex or any other suitable sealing composition to deposit on the outside of the box a layer 48 of rubber or the like.

It will be noted that a series of chambers 50 are defined at different levels within the pouch box 34 between the boards 42 and the diaphragms 46, the sides of these chambers being formed by the frames 40". All these chambers intercommunicate through apertures 52 formed in the boards 42 and the diaphragwms 46'. The bottom board 42 is formed with a vacuum inlet 54. As shown in Figure 10, the apertures 52 and the vacuum inlet 54 may all be arranged adjacent the rear wall er the pouch box 34. The lowermost chamber 50 is provided with a lateral outletdischarge tube 56. The upper faces of each board 42 are formed with a plurality of circular depressions 58 each connected to a vacuum tube 60 extending through the boards 42 and projecting rearwar'dly from the pouch box; Thus;. a plurality efc'ells 62 a'red'efinedby the depr'essions 58 and-sea led from the chambers 50 by the aphragms 46 A disc 64 of wood or the likeof' lessdiameter than the said cells 62 isconce'n tric'all-y' aflixed; as by an adhesive,- to the diaphragm's 46 aboveeach cell- 32. A- bar" or stripof wood 66 maybe adhesively afiix'ed toeachdisc' 64 in adirection normal to the operating-levers 32-. The inner ends ofthe1evers-32 rest on the bars 66% The front side of each frame 40' isforrned with a slot 68 for each lever 32. More particularly, the slots 68 are characterized-byrectangular horizontal cross-sectional shape A but have their upper surfaces inclined forwardly and outwardly; The levers 32 are fulcru-rned at the outer orifices of the'slots 6'8and, due to the form of these slots, may move upwardly and downwardly about their fulcra' but are restrained" pje'rn'cittingthe indicated movement ofth'e'lever's 32, also serve to seal the slots 68.

v springs 32 having upper ends anchoreden nails 14 o'n'thefront side of the ,pouch box" 34 urge the outer e'nds'of the'levers 32upwar'd1yl It will beunderstood that the ce1ls"62'arenormally maintained under a pressure not mucli higher, if at all, than the pressure in the chain,-

bers 5'0'and that the partsof the diaphragz'ns'fifi sealing the cells 62 are normally depressed be; low the upper surface level'or the boards 42', as shown in full lines in Figure 9." The springs 12 contribute to this end and alsoserve to insure positively a quick return of the levers-32 to their normally horizontal position. When outside'air is admitted into the cells62through the conduits BIL-the diaphragm part-overlying the cells 62" is causedtobulge,. asshown in dotted lines in Figs ure9-, thereby raising the inner ends of the levers 32 and depressing the outer ends sothatthe'wires 3D and the strips 20' arepulled-down-which actuate a keyubar' l8; As soon as air is no'longer: admitted into the cell; 62- through the conduit -60," an-dthe pressure within the cell-62 is againreducd-to a value not much-higher, if at; all, than that inthe ch'an'iber' fill, the diaphragm parts above the cell 62 return to their normal depressed position.

As shown in Figure 3, the levers 32 and the diaphragms are arranged in a number of horizontal rows corresponding to the frames 40. As between these horizontal rows, the levers 32 and diaphragms 10 are staggered horizontally, so that the levers and diaphragms are also arranged in rows extending at a slight angle with respect to the wires 30. The latter are of lengths such as to form a plurality of horizontal series arranged from left to right, the wires in each series being of progressively shorter length to engage operatively the outer ends of each of the inclined rows of levers 32.

The means for controlling the pressure in the cells 62 includes a tracker bar 16 shown in Figures 2, 6, 7 and 8. This part is formed with a lateral longitudinal slot 78 normally closed by a bar 80 held in place by screws 82. The pressure within the slot 18 as closed by the bar 80 is maintained at a reduced level, and for this purpose the bar I6 is provided with a tube 84 communicating with the slot I8. A series of constricted orifices 86 are provided for the slot I8 in the bar 16. The bar I6 is also provided, on its top surface, with a series of apertures 88 for a like number of tubes 90 extending normally up to and through the bar I6 into which the orifices 86 open. A tube 92 connects each tube 80 on the tracker bar 16 with a conduit 60 openin into a cell 62. A tube 94 connects the tube 84 on the tracker bar 16 with the tube 56 on the pouch box opening into a chamber 50.

A tube 96 connects the vacuum inlet conduit St on the pouch box 34 with a valve box 98 which, in turn, is connected to a vacuum pump (not shown).

A record reel I00 and a winding reel I02 driven by any suitable conventional means (not shown) are provided for movement over the upper surface of the tracker bar 16 of the record sheet I04 (see Figures 1 and 2). The record sheet has been punched to provide perforations I06 for controlling the operation of the pneumatic action.

As explained hereinabove, the action of the levers 32 is controlled by the pressure established within the cells 62. As also disclosed hereinabove, each cell 62 is connected through the conduits 60 and the tube 92 with a tube 90 in the tracker bar I6 communicating with the apertures 88 on the top surface of the tracker bar. Further, within the slot I8 a pressure is maintained ordinarily substantially the same as that within the chambers 50 in the pouch box 34, for the chambers 50 are connected with the slots I8 through the conduit 56, the tube 94 and the conduit 84. Normally, the pressure within the chambers 50 is about the same as the pressure within the cells 62. The restricted orifices 86 are not large enough to permit unrestricted flow so that difierences in pressures as between the chambers 50 and the cells 62 can be established and maintained for periods of time sufficiently long to bring about movement of the levers 32. It will, therefore, be understood that as the record sheet I04 passes over the upper surface of the tracker bar I6, this sheet normally closes the apertures 88 so that the cells 62 are maintained at about the same pressure as that within the chambers 50. But as an aperaperture is again closed by the record sheet by the movement of the aperture I06 past the aper ture 88, air that has been admitted is removed and reduced pressure reestablished in the cell 62 by suction through the restricted orifice 86 open= ing into the conduit 90.

While, as shown in Figure 6, a greater number of orifices 88 may be provided than the number of conduits connected to the cells 62, these additional orifices 88 not communicating with a cell 62 serve another purpose forming no part of the present invention, viz., that of controlling the reels I00 and I62 and other purposes. The mechanism employed for this purpose is not shown on the drawings.

The simplicity of the above described mechanism is evident. The parts most readily worn out or damaged are the diaphragms I0, and these may easily be replaced, since they are disposed on the outside of the pouch box 34. After repair or replacement of one of these diaphragms Ill, the whole pouch box may be dipped in rubber latex or other suitable sealing composition.

The above described pneumatic action is very easily attached to and disengaged from a typewriter. As shown in Figures 1 and 3, attachment may be eifected by placing the pneumatic action below a typewriter so that the connector strips 28 extend between the bars I8 with the connector ends 20a resting on the top of the bars I8. The typewriter may then be rigidly attached to the supporting member I2. Removable of the pneumatic action is equally easy.

Many details of construction may be varied without departing from the principles of this invention and it is, therefore, not my purpose to limit the patent granted on this invention otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. A pneumatic action comprising a hollow box-like member defining a chamber adapted to be connected to a source of vacuum for maintaining said chamber under reduced pressure, the inside of said chamberbeing shaped so as to define a plurality of cells, a flexible diaphragm closing off each of said cells from said chamber, a conduit for each cell extending through a wall of said box-like member, a slot through a wall of said box-like member for each cell, a lever fulcrumed in each slot, and a flexible diaphragm attached about each lever at its fulcrum point and sealing said slot, said levers being movable about their fulcra in saidslots under the influence of the diaphragms closing off said cells as air is selectively admitted to and withdrawn from said cells whereby said levers can be utilized to actuate selectively a mechanism having a plurality of members to be actuated.

2. A pneumatic action for a mechanism having a plurality of members to be actuated under the control of a record sheet, said action comprising a tracker bar formed with an internal longitudinal chamber, a conduit whereby said chamber can be maintained under reduced pressure, a plurality of transverse conduits extending along and outside one margin of said chamber and normally closed by a record sheet passing over said tracker bar but selectively opened momentarily by apertures in said record sheet and constricted orifices connecting said conduits with said chamber; a hollow box-like member defining a second chamber adapted to be connected with a source of vacuum for maintaining said second chamber under reduced pressure, the .inside of said chamber being shaped so as to define a plurality of cells and said box-like member being formed with a slot through a wall of said box-like member for each cell; a flexible diaphragm closing off eachof said cells from said second chamber; a conduit for each cell extending througha wall of sai'd box-like member and connected to one of said tracker bar conduits; a lever fulcrumedin each of said slots; at flexible diaphragm attached to each lever at is fulcrum point and sealing said slot; conduit means con nectingsaid first and second chambers; and a plurality of links for operatively connecting said levers with said members to be actuated selectively, said levers being movable about their fulera in said slots-under the influence of saiddiaphragms closing off said cells so that as air is selectively admitted into said tracker bar through record sheet apertures one of said cell closing diaphragrns will be moved and the resultingv movement'will be transmitted through one of said levers and said links to a member to be actuated.

3; A pneumatic action comprising a hollow box-like member defining a' chamber adapted to be connected to a source of vacuum for maint'aining said chamber under reduced pressure, a wall of said chamber being formed-so as to define a' plurality of cells, a flexible diaphragm closing off each of said cells from said chamber, a conduit for each cell extending through said wall of said chamber, one" other wall of said chamber being formed with slots each aligned with one of said cells, a lever fulcrumed in each slot; a flexible diaphragm attached about each lever at its fulcrum point and sealing the outer opening of said slot, and resilient means for said leversurging the inner lever ends toward said cell closing diaphragms.

4. A pneumatic action comprising a hollow box-like member defining a plurality of intercommunicating chambers adapted to be connected to a source of vacuum for maintaining said chambers under reduced pressure, the bottom of each of said chambers being formed so as to define a plurality of cells, a flexible diaphragm closing 01? each of said cells from said chambers, a conduit for each cell extending through the bottoms of said chambers, one side wall of each of said chambers being formed with slots each aligned with one of said cells, a lever fulcrumed in each slot, a flexible diaphragm attached about each lever at its fulcrum point and sealing the outer opening of said slot, resilient means for said levers urging the inner lever ends toward said cell closing diaphragms and a rigid member disposed above each cell on said diaphragms adapted to contact the inner ends of said levers when air is admitted into said cells.

5; Apneumatic action comprising a plurality of rectangular frames each formed with a series of slots in one side wall, a' bottom panel for each frame formed so as to define on its upper side a plurality of cells each aligned with one slot, a closure" panel, said frames and bottom panels being stacked alternately and having said closure panel superposed on the resulting=stack to form a generally box-like member-defining-a plurality of chambers, all of said bottom panels except the lowermost bottom panel being apertured to provide interc'ommunication between said chambers, said chambers being adapted-to be maintained" under reduced pressure, a flexible diaphragm closing off each of said cells from said chambers, a conduit foreach' cell extending through said bottom panels; alever fulcrumed 8 in each slot, and a flexible diaphragm attached about each lever at its fulcrum point and sealing: the outer. opening of said slot.

6; A pneumatic action comprising a plurality of rectangular frames each formed with a series of. slots in one sidewall, .a bottom panel for each frame formed so as to define on its upper side a plurality of cells aligned with said slots, a

diaphragm overlying each bottom panel and sealing oil the cells therein, a closure panel, setsof said frames, diaphragms and bottom panels being assembled together and the resulting assem'blies being stacked and having said closure panel superposed on the resulting stack to form a box-like member defining a plurality of chambers, all except the lowermost bottom panel being apertured to provide intercommunication 'between said chambers, said chambers being adapted to be maintained under reduced pressure, a lever fulcrumed in each slot, and a flexible diaphragm attached about each lever at it' fulcrum point and sealing the outer opening of said slot: '7. A pneumatic action comprising'a hollow boxlilre member defining a plurality of intercomunicating chambers adapted to be connected to a source of vacuum for maintaining said chambers under reduced pressure, the bottoms of said chambersbeing'formed so as to define a plurality of cells, a flexible diaphragm closing off each of said cells from said chambers, a conduit for each cell extending through the bottoms of said chambers and opening on one side of said box-like member, the other side of the box-like member being formed with a plurality of slots each aligned with one of said cells and each tapering outwardly, a lever fulcrumed in each of said slots at its outer opening, and a flexible diaphragm attached about each lever at its fulcrum point and sealing the outer opening of said slot.

8. A pneumatic action comprising a hollow box-like member defining a plurality of intercommunicating chambers adapted to be connected to a source of vacuum for maintaining said chambers under reduced pressure, the bottoms of said chambers being formed so as todefine a plurality of cells, a flexible diaphragm closing off each of said cells from said chambers, a conduit for each cell extending through one side of said box-like member; the other side of the box like member being formed with a plurality of slots each aligned'with one of said cells and each having'flat vertical sides tapering outwardly, a lever flat vertical sides in each slot and fulcrumed at the outer opening thereof, and a flexible diaphragm attached about each lever at its fulcrum point and sealing the outer opening of said slot.

9. A pneumatic action comprising a hollow box-like member defining a plurality of intercommunicating chambers adapted to be connected to a'source of vacuum for maintaining said chambers under reduced pressure, the bottoms of said chambers being formed so asto define a plurality of cells, a flexible diaphragm closing oil each of said .cells from said chambersja conduit for each cell extending through the bottoms of said chambers and all opening on one side of said box-like member, the other side of'said box-like member being formed with slots each aligned with one of said cells, a lever fulcrumed in each slot, a flexible diaphragm attached'about each lever at its fulcrum point and sealing the outer opening of said slot, and links operatively connected to said levers extending over said second side of said box-like member.

10. A pneumatic action comprising a hollow box-like member defining a plurality of intercommunicating chambers adapted to be connected to a source of vacuum for maintaining said chambers under reduced pressure, the bottoms of said chambers being formed so as to define a plurality of cells, a flexible diaphragm closing off each of said cells from said chambers, a conduit for each cell extending through the bottoms of said chambers and all opening on one side of said box-like member, the other side of said boxlike member being formed with slots each aligned with one of said cells, a lever fulcrumed in each slot, a flexible diaphragm attached about each lever at its fulcrum point and sealing the outer opening of said slot, links operatively connected to said levers extending over said second side of said box-like member beyond the top of said boxlike member, a housing for said action apertured to permit said links to project therethrough, and link guides supported from said housing for confining the movement of said links to reciprocation normally of said levers.

11. A pneumatic action for a typewriter or like mechanism having a plurality of members to be actuated under the control of a record sheet, said action comprising a tracker bar formed with an internal longitudinal chamber, a conduit whereby said chamber can be maintained under reduced pressure, a plurality of transverse conduits extending along and outside one margin of said chamber and normally closed by a record sheet passing over said tracker bar but selectively opened momentarily by apertures in said record sheet and constricted orifices connecting said conduits with said chamber; a hollow box-like member defining a second chamber adapted to be connected with a source of vacuum for maintaining said second chamber under reduced pressure, the inside of said chamber being shaped so as to define a plurality of cells and said box-like member being formed with a slot through a wall of said box-like member for each cell; a flexible diaphragm closing off each of said cells from said second chamber; a conduit for each cell extending through a wall of said box-like member and connected to one of said tracker bar conduits; a lever fulcrumed in each of said slots; a flexible diaphragm attached to each lever at its fulcrum point and sealing said slot; conduit means connecting said first and second chamhers; a plurality of links for operatively connecting said levers with said members to be actuated selectively, said levers being movable about their fulcra in said slots under the influence of said diaphragms closing off said cells so that as air is selectively admitted into said tracker bar through record sheet apertures one of said cell closing diaphragms will be moved and the resulting movement will be transmitted through one of said levers and said links to a member to be actuated, a housing for said action adapted to be disposed underneath the typewriter with said links projecting upwardly from said housing; and guide means supported from the top of said housing for confining the movement of said links to vertical reciprocation.

12. A pneumatic action comprising a plurality of rectangular frames each formed with a series of slots in one side wall, a bottom panel for each frame formed so as to define a plurality of cells aligned with said slots, a diaphragm overlying each bottom panel and sealing off the cells therein, a closure panel, sets of said frames, diaphragms and bottom panels being assembled together and the resulting assemblies being stacked and having said closure panel superposed on the resulting stack to form a box-like member defining a plurality of chambers, all except the lowermost bottom panel being apertured to provide intercommunication between said chambers, said chambers being adapted to be maintained under reduced pressure, a conduit for each cell extending through said bottom panels, a lever fulcrumed in each slot, a flexible diaphragm attached about each lever at its fulcrum point and sealing the outer opening of said slot, a housing for said action, U-shaped members encompassing said box-like member and projecting through one side of said housing, and means for fixedly holding the projecting portions of said members on the outside of said housing to maintain said boxlike member in position on the inside of said housing.

GUSTAV F. CARISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,285,444 Kloid June 9, 1942 2,327,172 Carlson Aug. 17, 1943 

